A NEW FOSSIL CANID ASSEMBLAGE FROM THE LATE

J. Paleont., 81(5), 2007, pp. 1053–1065 Copyright 䉷 2007, The Paleontological Society 0022-3360/07/0081-1053$03.00

A NEW FOSSIL CANID ASSEMBLAGE FROM THE LATE PLEISTOCENE OF NORTHERN SOUTH AMERICA: THE CANIDS OF THE INCIARTE ASPHALT PIT (ZULIA, VENEZUELA), FOSSIL RECORD AND BIOGEOGRAPHY FRANCISCO J. PREVOSTI1

AND

´ N2 ASCANIO D. RINCO

Departamento Cientı´fico Paleontologıá Vertebrados, Museo de La Plata, Paseo del Bosque S/No, 1900 La Plata, Buenos Aires, Argentina, Consejo Nacional de Investigaciones Cientı´ficas y Tećnicas (CONICET), ⬍[email protected]⬎; and 2Lab. Biologıá de Organismos, Centro de Ecologıá, Instituto Venezolano de Investigaciones Cientificas (IVIC), km 11 de la Carretera Panamericana, Apartado Postal 21827, Caracas 1020-A Venezuela, ⬍[email protected]⬎ 1

ABSTRACT—Canids invaded South American during the Pliocene (2.8–3.1 Ma BP) as part of the Great American Biotic Interchange, but their record on the continent is relatively poor until the Pleistocene. However, even the Pleistocene record of the group is patchy and biased, with few records for the northern part of South America. In this paper we describe a new assemblage of canids found at the Inciarte asphalt pits (Zulia, Venezuela). These remains are associated with a variety of extinct Pleistocene mammals dated between 25–27 Ka BP. Canids in this assemblage include Protocyon troglodytes (Lund 1838), Protocyon sp., Canis dirus Leidy, 1858, Urocyon cf. U. cinereoargenteus (Schreber, 1775), and an indeterminate canid. This is the first record of Urocyon Baird, 1758 from the Late Pleistocene in South America and constrains the timing of its dispersal to South America. The distributional record of Protocyon Giebel, 1855 and P. troglodytes is expanded 1,500 km north of previous records and constitutes the first record of these taxa in Venezuela. The presence of C. dirus at Inciarte constitutes the fourth locality for this species in South America.

INTRODUCTION

C

in North America and have a high diversity during the Tertiary on that continent. It is only in the Late Miocene that the group expanded its geographic distribution to other continents (Wang, 1994; Wang et al., 1999, 2004). The history of the South American canids is closely related to the formation of the Panamanian Land Bridge around 2.8–3.1 Ma BP (Coates and Obando, 1996; Coates, 2003), a tectonic event that triggered the biogeographic event called the ‘‘Great American Biotic Interchange’’ (Webb, 1991, 1999; Campbell et al., 2000; Cione and Tonni, 2001; Morgan, 2002; Carranza-Castan˜eda and Miller, 2004; Flynn et al., 2005; Kirby and MacFadden, 2005). The earliest canid record in South America comes from the Late Pliocene (Marplatan Age, Vorohueian Subage, 2.5–3 Ma BP; Cione and Tonni, 2001) of the Pampean Region (Argentina, Fig. 1), and has been assigned to the genus Dusicyon Hamilton Smith, 1839 (which includes Pseudalopex Burmeister, 1856; Berman, 1994). Other genera (e.g., Protocyon Giebel, 1855; Theriodictis Mercerat, 1891; Chrysocyon Hamilton Smith, 1839) first appear in the Early-Middle Pleistocene (Ensenadan age) or younger faunas (Berta, 1987, 1988; Berman, 1994; Prevosti et al., 2004, 2005). Our knowledge of these canids is restricted to a limited and scattered number of localities. The most nearly continuous record for the group is from the Pampean Region, where extensive Late Pliocene, Pleistocene, and Holocene outcrops contain a rich diversity of canids and other taxa (e.g., L. Kraglievich, 1928, 1930; Berta, 1988; Berman, 1994). Other important localities with fossil canids are Tarija, Bolivia (Middle-Late Pleistocene; Hoffstetter, 1963, 1986; Dundas, 1999; MacFadden, 2000), and the Late Pleistocene deposits of Lagoa Santa, Brazil (Lund, 1950; Cartelle, 1999). The asphalt pits of Talara, Peru, and La Carolina, Ecuador, have produced a large sample of Late Pleistocene canids (Hoffstetter, 1952; Churcher, 1959). While isolated records are known from other Pleistocene localities (e.g., Berta, 1988; Dundas, 1999), canids are virtually absent from the northern portion of South America (i.e., Colombia, Venezuela, Guyana, Surinam) with the exception of Canis dirus Leidy, 1858 from the Late Pleistocene site of Muaco, Falcoń State, Venezuela (Royo y Go´mez, 1960; Berta, 1988; Fig. 1). These biases have complicated the reconstruction of the evolution of this group in South America and the testing of biogeographical hypotheses (e.g., Berta, 1988). In this paper we describe a new canid assemblage from the Late Pleistocene (25–27 Ka BP) of the asphalt pits of Inciarte, a ANIDS ORIGINATED

new fossil locality from the state of Zulia in western Venezuela. This assemblage includes Protocyon troglodytes (Lund, 1838), Protocyon sp., Canis dirus, and Urocyon cf. U. cinereoargenteus (Schreber, 1775). The record of Urocyon cf. U. cinereoargenteus in this paper is the first fossil occurrence of the genus in South America, while the geographic range of Protocyon and P. troglodytes is expanded from southern Ecuador (Santa Elena) and northeastern Brazil (Bahia) to Venezuela (see Fig. 1). The implications of these records are discussed in the context of the South American fossil record and a published biogeographic hypothesis (e.g., Berta, 1988). MATERIALS AND METHODS

Measurements were taken using dial calipers with 0.05 mm precision and are listed in Tables 1–4. The cusp terminology follows Wang et al. (1999) but has been modified in order to adapt it to the orientation nomenclature proposed by Smith and Dodson (2003) (e.g., posterior accessory cusp was changed to distal accessory cusp). Other anatomical nomenclature follows Evans (1993). We also follow the biostratigraphic and chronostratigraphic scheme of Cione and Tonni (2001), and, the systematics of Berta (1987, 1988). Anatomical abbreviations.⎯I/i, upper/lower incisor; C/c, upper/lower canine; P/p, upper/lower premolar; M/m: upper/lower molar; D, deciduous. Measurement abbreviations.⎯HFM, height of the foramen magnum; L, length (mesiodistal in teeth); LAst, length of the astragalus; LB, length of the tympanic bulla; LCalc, maximum length of the calcaneum; LCub, proximodistal length of the cuboid; LDHum, anteroposterior length of the distal portion of the humerus; LLa, labial length; LLi, lingual length; LMc1, length of the first metacarpal; LMc2, length of the second metacarpal; LMc4, length of the fourth metacarpal; LNav, proximodistal length of the navicular; LPEsc, anteroposterior length of the proximal portion of the scapula; LPTib, anteroposterior length of the proximal articular facet of the tibia; LSac, length of the sacrum between the anterior and posterior articular facets; LSca, anteroposterior length of the scapholunar; Ltr, length of the trigonid; LTuCalc, length of the calcanear process of the calcaneum; W, width (labiolingual in dents); WAst, width of the astragalus at the trochlea; WB, width of the tympanic bulla; WCO, width between the lateral borders of the occipital condyles; WCub, transverse width of the cuboid; WDHum, transverse width of the distal humerus; WFM, width of the foramen magnum; WNav, transverse length of the navicular; WPEsc, width of the proximal portion of

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JOURNAL OF PALEONTOLOGY, V. 81, NO. 5, 2007

FIGURE 1—Location map of Inciarte asphalt pits and other South American fossil localities with canids. 1: Inciarte; 2: Muaco; 3: La Carolina; 4: Talara; 5: Northeastern Brazil; 6: Lagoa Santa; 7: Tarija; 8: Pampean Region.

the scapula; WSca, transverse width of the scapholunar; WPTib, transverse length of the proximal articular facet of the tibia; Wta, width of the talonid Wtr, width of the trigonid. Institutional abbreviations.⎯MBLUZ-P, Seccioń de Paleontologıá of the Museo de Biologıá de La Universidad del Zulia, Maracaibo, Venezuela; MNHN, Museum Nationale d’Histoire Naturelle, Paris, France; UZM L, Peter W. Lund Collection, Universitets Zoologiske Museum, Copenhagen, Denmark; VF, Museo Royo y Go´mez, Departamento de Geologıá de la Universidad Central (Caracas, Venezuela). INCIARTE: GEOGRAPHIC STRATIGRAPHIC, AND PALEOENVIRONMENTAL CONTEXT

The Inciarte asphalt pit (10⬚47⬘42.6⬙N–72⬚14⬘20.8⬙W) is located near the Cachirı´ River along the foothills of the Perija´ Mountains in the state of Zulia (Venezuela; Fig. 1). Inciarte is located in the ‘Caribenã Zuliana’ biogeographic province (Linares, 1998), and the vegetation of this locality is brushy and dominated by Byrsonima crassifolia (L.) Kunth, 1822. This asphalt deposit was

commercially exploited during the twentieth century (Urbani and Galarraga, 1991), but the presence of fossil vertebrates was recorded later in 1997 by the geologist John Moody (see McDonald et al., 1999). The surface area of the asphalt is about 1,200 sq m in a northeast-southwest direction with a maximum width of 400 m. The surface is partially consolidated with some liquid asphalt ponds. The asphalt has seeped through Pleistocene terrace deposits (Urbani and Galarraga, 1991). At Locality 198 we have excavated a trench 1.30 m deep and have identified three stratigraphic levels: the upper level, 25 cm thick, is composed of a very fine silt, without asphalt and fossils; the middle level, 70 cm thick and composed of 80% asphalt and 20% sand, contains a large number of fossils; the lower level, with an exposed depth of 30 cm, has a high proportion of sand (20%) and also contains a great number of fossils (Rincoń, 2005; Czaplewski et al., 2005). The remains collected at Locality 185 came from removed sediments from levels stratigraphically higher than locality 198, and separated by a fault (Rincoń, 2005). A rich fossil vertebrate assemblage has been found at Inciarte comprised of glyptodonts, ground sloths, equids, camelids, mastodons, and bats (McDonald et al., 1999; Rincoń, 2005; Czaplewski et al., 2005) dated between 25.5 ⫾ 0.6 and 27.98 ⫾ 0.37 Ka BP (Jull et al., 2004). The fauna suggests that the environment of the lower level was a savannah, while at the upper level, the indicated climate was more humid and the vegetation more closed (Rincoń, 2005; see also Czaplewski et al., 2005). SYSTEMATIC PALEONTOLOGY

Order CARNIVORA Bowdich, 1821 Suborder CANIFORMIA Kretzoi, 1943 Family CANIDAE Fischer, 1817 Genus PROTOCYON Giebel, 1855 PROTOCYON TROGLODYTES (Lund, 1838) Figure 2; Table 1 Canis spelaeus LUND, 1837, p. 324, pl. 2, figs. 2, 4. Canis troglodytes LUND, 1838, p. 60. Palaeocyon validus LUND, 1843, p. 54. Canis lycodes LUND, 1843, p. 49–50, pl. 45, fig. 3. Protocyon troglodytes (LUND, 1838), GIEBEL, 1855, p. 851. Canis musculosus AMEGHINO, 1882, p. 38 (nomen nudum). Description.⎯The P3 presents an elliptic shape in occlusal view and bears a well-developed distal accessory cusp, with high, acute, and slender principal cusps. The distal cingulum is scarcely developed. MBLUZ-P-4727 lacks the distal accessory cusp and its principal cusp is blunter. The P2 shows the same morphological pattern as the P3, but is smaller and generally lacks the distal accessory cusp (only the MBLUZ-P-2541 bears this cusp). The P4 is large and elongated, with an extremely reduced and lingually oriented protocone and a strong paracrist on its mesial face. The lingual cingulum is poorly developed, and the labial border of the metastyle is displaced lingually with respect to the labial border of the paracone. The p2 possesses a high principal cusp with straight mesial and distal borders but lacks accessory or cingular

TABLE 1—Dental measurements (mm) of Protocyon troglodytes (Lund, 1838) and C. dirus Leidy, 1858 from Inciarte (Zulia, Venezuela). Specimen

LI3

P. troglodytes MBLUZ-P-2626 MBLUZ-P-2541 MBLUZ-P-4351 MBLUZ-P-4727 MBLUZ-P-3953 MBLUZ-P-2221 MBLUZ-P-4498 MBLUZ-P-2393 MBLUZ-P-2337 MBLUZ-P-2579 C. dirus MBLUZ-P-1941 MBLUZ-P-2388 12.05

WI3

8.4

LP2

WP2

11.45 11.45

5.6 5.9

10.85

5.4

LP3

WP3

12.05

6.25

11.95

6

11.55

5.95

LP4

WP4

26.4

11.95

Lp2

Wp2

10.05

5.6

Lp4

18.9

Wp4

9.9

Lm1

Ltrm1 Wtam1 Wtrm1

26.5 27

20 20.15

8.2 8.3

10.5 10.65

PREVOSTI AND RINCON—PLEISTOCENE CANIDS FROM THE LATE PLEISTOCENE OF VENEZUELA

1055

FIGURE 2—Protocyon troglodytes (Lund, 1838). Left P4 (MBLUZ-P-4498) in occlussal (1), lingual (2), and labial (3) views. Right P3 (MBLUZ-P-4351) in lingual (4) and labial (5) views. Right P2 (MBLUZ-P-2541) in labial (6) and lingual (7) views. Left p2 (MBLUZ-P-2393) in lingual (8) and labial (9) views. Right m1 (MBLUZ-P-2334) labial (10) and lingual (11) views. Left m1 (MBLUZ-P-2579) labial (12) and lingual (13) views.

cusps. The m1 has a long trigonid but a short and narrow talonid. The metaconid, protostylid, and entoconid are absent in this molar. MBLUZ-P-2579 has a small enamel bulge in the position of the metaconid. On the distal face of the protoconid there is a well-developed protocristid, and in MBLUZ-P2337 there is a cristid on the lingual side. A cingulum appears at the position of the entoconid. The labial border talonid is lingually displaced with respect to the labial margin of the trigonid. Material examined.⎯MBLUZ-P-4498: left P4; MBLUZ-P-2337: fragment of right mandible with the m1; MBLUZ-P-2579: fragment of right mandible

with the m1; MBLUZ-P-2626: right P3; MBLUZ-P-2541: right P2; MBLUZP-4351: right P2; MBLUZ-P-4727: left P3; MBLUZ-P-2393: left p2; MBLUZ-P-3953: left P2; MBLUZ-P-2221: left P3. Occurrence.⎯Locality 198 of Inciarte (Zulia, Venezuela), middle and upper levels.

Discussion.⎯The size of the specimens (Table 1) is within the observed range of Protocyon and generally smaller than Theriodictis, but there is some overlap; they are smaller than South American

1056


FIGURE 3—Dental specimens of Protocyon sp. from Inciarte (Zulia, Venezuela). Labial (1) and occlusal (2) views of left M1 (MBLUZ P 4380). Lingual (3) and labial (4) views of left I3 (MBLUZ-P-2556). Lingual (5) and labial (6) of right Dc1 (MBLUZ-P-4008). Right Dp4 (MBLUZ-P-4603) in lingual (7) and labial (8) views. Right C1 (MBLUZ P 3222) in labial (9) and lingual (10) views.

species of Canis Linnaeus, 1758 (see Merriam, 1912; L. Kraglievich, 1928; Churcher, 1959; Berta, 1988; Prevosti et al., 2004). The combination of the following characters clearly separates these specimens from Canis, Theriodictis, and Chrysocyon: an acute and weak principal cusp in the premolars, with the distal border more concave than in Chrysocyon; large P4 with protocone and lingual cingulum reduced; and an m1 without metaconid and entoconid. Three species of Protocyon are currently recognized; P. troglodytes, P. scagliarum J. L. Kraglievich 1952, and P. orcesi Hoffstetter 1952 (Berta, 1988; Prevosti et al., 2005). Recently, Cartelle and Langguth (1999) suggested that P. scagliarum is a junior synonym of P. troglodytes, but that P. orcesi is a distinct and more specialized species than P. troglodytes. The revision of the group by one of us (Prevosti, personal observations), as part of his Ph.D. thesis, is contrary to this hypothesis. The only known specimen of P. scagliarum is the holotype, a skull found in the Pampean Region (Buenos Aires, Argentina; Fig. 1) (Berta, 1988; Berman, 1994). This specimen presents a suite of characters (e.g., premolars with very high and acute principal cusps; zygomatic arches slender and not transversally expanded; paraoccipital process only fused to the bulla at its base) that distinguishes it from

other species of the genus. It is not clear that all of these characters correspond to intraspecific variation; thus it is premature to consider P. scagliarum a synomym of P. troglodytes. However, P. orcesi is very similar to P. troglodytes, but it lacks the m3 and the trigonid of the m2 is proportionally narrower (Berta, 1988; Cartelle and Langguth, 1999). Some specimens of the latter species (e.g., MNHN NUA 91) possess an m2 with the same morphology and proportions found in P. orcesi. In Recent canid species the presence of the m3 and the shape of the m2 are variables (Mivart, 1890; L. Kraglievich, 1930; Buchalczyk et al., 1981; Steenkamp and Borrel, 1999; Szuma, 2002; Prevosti et al., 2004), and suggest that P. orcesis is a junior synonym of P. troglodytes. The premolars from Inciarte have lower and less acute principal cusps than in P. scagliarum, and the protocone of the P4 is more reduced than in the latter species. The m1 from Inciarte is slightly larger than that of P. scagliarum, and the talonid is proportionally narrow to the trigonid width. The size and morphology of these specimens allow assigning them to P. troglodytes. PROTOCYON sp. Figures 3, 4; Tables 2, 3 Description.⎯MBLUZ-P- 3896 lacks a diastema between the alveolus of the p2–p3, and the mesial locus of the p2 alveolus is displaced labially with


1057

FIGURE 4—Postcranial specimens of Protocyon sp. from Inciarte (Zulia, Venezuela). Anterior view (1) of left second metacarpal (MBLUZ P 2867). Anterior view (2) of left fourth metacarpal (MBLUZ P 2915). Right astragalus (MBLUZ P 3243) in proximal (3) and distal (4) views. Medial (5) and distal (6) views of right cuboid (MBLUZ P 2440). Proximal fragment of left scapula (MBLUZ P 3711) in lateral view (7). respect to the distal one. The size of the P4 alveolus of MBLUZ-P-4726 shows that this premolar was proportionally very large. The P3 has a high and acute principal cusp. The principal cusp of the I1 is low in comparison with the accessory cusps, and the lingual cingulum is weakly developed. This incisor possesses a mesial accessory cusp placed at a higher position than the distal accessory cusp. The I2 is larger than the I1 and presents a similar morphological pattern, but with a proportionally larger principal cusp. The I3 is very large and has a robust caniniform first cusp, which is distally curved. It has a weak mesiolingual cingulum, and sharp distal and mesiolabial crists. The canines are short, straight, and robust, with sharp distal and mesiolabial crists. The P1 has a subtriangular transverse section, a strong principal cusp, a sharp mesiolingual crist, but a weakly developed lingual cingulum. M1 shows a large, conical, and tall paracone, which bears distal and mesial crists. The metacone is relatively small and low, and the labial cingulum is extremely reduced and only observable at the mesial portion of the paracone. The protocone has a pyramidal form, but is smaller than the metacone, connected to strong and crenulated pre and postprotocrists. The metaconule is a

slight inflection of the postprotocrist. The hypocone is a small distolingual cingulum encircling the mediolingual border of the protocone. The M1 shows a concave distal border. The i2 has a large principal cusp and a small distal accessory cusp. The i3 presents a similar morphology, but it is larger, and the principal cusp is proportionally larger and higher. Both incisors present poorly developed lingual cingula that do not form a ‘platform’ as in the uppers. The existence of mesial accessory cusp on the i1–3 could not be checked because of dental wear. The p1 is very similar to the P1, but possesses a higher and more slender principal cusp. The roots of the Dc1 are broken and have thin walls. The principal cusp is robust and curved, and shows a cristid along its mesiolingual border. The Dp4 has a tall protoconid, a relictual metaconid, a sharp protocristid, and a hypoconid, but lacks the entoconid. The scapula has a rounded glenoid cavity, a strong coracoid process, and a robust and blunt acromion. The metacromion is robust but small. The radius presents a straight diaphysis with open sutures and lacks the epiphysis. The trochlea of the astragalus has a deep groove and a wide, elliptic head that is

5.15

5.3

5.7

5.2

4.8

4.5

5

WI1

4.8

LI1

5.25

5.1

5.25*

LI2

6.25

6.25

6.9

WI2

8.2

8.83 8.9

LI3

6.8

6.6 6.75

WI3

10.65 11.6 11.25*

LC1

7.3 7.85 8.5*

WC1

7.25 6.25 7.8

LP1

WPEsc

21.4

Specimen

Protocyon sp. MBLUZ-P-2867 MBLUZ-P-2915 MBLUZ-P-3243 MBLUZ-P-4283 MBLUZ-P-3201 MBLUZ-P-2440 MBLUZ-P-3711 Canidae indet. MBLUZ-P-6581 MBLUZ-P-2072 MBLUZ-P-2596 MBLUZ-P-2108 MBLUZ-P-4714 MBLUZ-P-2190

34.25

LPEsc

12.55

17.45

23.2

LDHum WDHum Wsca

14.35

Lsca

24.05 25

LMc1 62.35

LMc2

76.15

LMc4

49.75

LPTib

5.05 4.45 5.4

WP1

TABLE 3—Postcranial measurements (mm) of Protocyon sp. and Canidae indet. from Inciarte (Zulia, Venezuela).

MBLUZ-P-4380 MBLUZ-P-2389 MBLUZ-P-2462 MBLUZ-P-3222 MBLUZ-P-3042 MBLUZ-P-1763 MBLUZ-P-4499 MBLUZ-P-2556 MBLUZ-P-3599 MBLUZ-P-2846 MBLUZ-P-2840 MBLUZ-P-2872 MBLUZ-P-4126 MBLUZ-P-3335 MBLUZ-P-3143 MBLUZ-P-4242 MBLUZ-P-3636 MBLUZ-P-4624 MBLUZ-P-4319 MBLUZ-P-4163 MBLUZ-P-4613 MBLUZ-P-3684 MBLUZ-P-3979 MBLUZ-P-4923 MBLUZ-P-3881 MBLUZ-P-2652 MBLUZ-P-3652 MBLUZ-P-4169 MBLUZ-P-4116

Specimen

TABLE 2—Dental measurements (mm) of Protocyon sp. from Inciarte (Zulia, Venezuela). *: approximation.

42.65

WPTib

15 15.1

LLaM1

28.65 30

LAst

9.3 10.01* 9.95

LLiM1

18.55 18.7

WAst

17.05

WM1

3.8

4.1

3.95 3.7

Wi2

24.6

LCalc LTuCalc

4.95

5.05

5 4.85

Li2

17.55

15.65

LNav

6

6

Li3

16.45

WNav

5.45

5.65

Wi3

17.3

LCub

5.8 6.48 6 6.45

Lp1

15.3

WCub

4.25 4.5 4.5 4.5

Wp1

1058 JOURNAL OF PALEONTOLOGY, V. 81, NO. 5, 2007

PREVOSTI AND RINCON—PLEISTOCENE CANIDS FROM THE LATE PLEISTOCENE OF VENEZUELA medially expanded with respect to the trochlea and has an angular shape. The major axis of the head forms a 45⬚ angle with the transverse plane of the trochlea. There is a small foramen on the proximal border of the trochlea of one astragalus (MBLUZ-P-3242), inside its groove (the ‘perforacioń astragaliana’ of Ameghino, 1906; see Wang, 1993). But in MBLUZ-P-4283 only a shallow groove can be observed in this position. The cuboid has a large plantar tubercle that occurs along the entire plantar surface. The medial process and the sulcus for the tendon of the muscle peroneus longus are well developed. The first one is positioned halfway between the distal and proximal faces. The tubercle that forms the dorsal limit of the sulcus for the the tendon of the muscle peroneus longus does not reach the proximal articulation of the bone. The metacarpals possess robust diaphyses, and well-developed distal heads, sesamoid fossi, and a ventral keel on their distal extremity. The second metacarpal is laterally curved but the diaphyses of the third and fourth metacarpals are straighter. The second and third metacarpals present subtriangular proximal articular facets, whereas these adopt a rectangular form on the fourth metacarpals. Material examined.⎯MBLUZ-P-3896: fragment of right mandible with the alveolus of the p2-p3; MBLUZ-P-4726: fragment of left maxillary with the P3 inside its alveolus; MBLUZ-P-3042: left C1; MBLUZ-P-3222: right C1; MBLUZ-P-1763: left C1; MBLUZ-P-4499: right I3; MBLUZ-P-2556: left I3; MBLUZ-P-4380: left M1; MBLUZ-P-2389: incomplete left M1; MBLUZ-P2462: incomplete left M1; MBLUZ-P-4008: right Dc1; MBLUZ-P-2957: left Dc1; MBLUZ-P-4126: left P1; MBLUZ-P-2872: left p1; MBLUZ-P-3599: right p1; MBLUZ-P-2846: right p1; MBLUZ-P-3335: right P1; MBLUZ-P3143: right P1; MBLUZ-P-4242: right I1; MBLUZ-P-3636: left I2; MBLUZP-4624: right i2; MBLUZ-P-4319: right i2; MBLUZ-P-4163: left I3; MBLUZP-4613: right I1; MBLUZ-P-3684: left I2; MBLUZ-P-3979: right i2; MBLUZ-P-4923: right I1; MBLUZ-P-3881: right i3; MBLUZ-P-2652: left i2; MBLUZ-P-3652: right I2; MBLUZ-P-4777: left Dc1; MBLUZ-P-2840: right p1; MBLUZ-P-4169: left I1; MBLUZ-P-4116: left i3; MBLUZ-P-4603: incomplete right Dp4; MBLUZ-P-3711: proximal fragment of left scapula; MBLUZ-P-4263: right radius without ephiphysis; MBLUZ-P-3243: right astragalus; MBLUZ-P-4283: right astragalus; MBLUZ-P-2440: right cuboid; MBLUZ-P-2867: left second metacarpal; MBLUZ-P-2915: left fourth metacarpal; MBLUZ-P-1976: proximal fragment of left third metacarpal; MBLUZP-4700: left third metacarpal without the distal epiphysis. Occurrence.⎯Locality 198 of Inciarte (Zulia, Venezuela), middle Level, with the exception of the MBLUZ-P-4700 that has been found at the lower level.

Discussion.⎯These specimens are smaller than Theriodictis and the South American species of Canis, and similar in size to Protocyon (see Winge, 1895; Merriam, 1912; L. Kraglievich, 1928; Nigra and Lance, 1947; Stock and Lance, 1948; Churcher, 1959; Nowak, 1979; Kurteń, 1984; Berta, 1988; Cartelle and Langguth, 1999; Figs. 3, 4; Tables 2, 3). The crowded alveoli for the premolars in MBLUZ V 4726 is another character shared with Protocyon (Cartelle and Langguth, 1999). The morphology of the principal cusp of the P3 and the size of the alveolus of the P4 in the MBLUZ-P-4726 also agree with Protocyon. Other characters that allow us to distinguish these specimens from C. dirus and Chrysocyon brachyurus (Illiger, 1815) include the large caniniform I3 with reduced lingual cingulum; short and robust principal cusp; M1 with reduced hypocone and labial cingulum; and Dp4 with reduced metaconid and entoconid absent. Additionally, the lingual cingula of the I1–2 are more reduced than in Canis, but the lingual cusps are proportionally larger than in Chrysocyon. In the latter genus the distal accessory cusps of the i2–3 are also more reduced. The P1/p1 are more acute and high, and the lingual cingulum is weaker than in C. dirus. Chrysocyon has a P1/p1 with a more slender principal cusp and presents a less concave distal border. The morphology of the Dp4 is very similar to the specimen of P. troglodytes (UZM L 6581), but the metaconid and the lingual cingulum of the talonid are further reduced. The Dc1 of Protocyon is not known, but the size and morphology of the specimens found at Inciarte fit well with the expected characteristics. The size and proportions of the postcranial remains separate it from Theriodictis, Ch. brachyurus, and C. dirus, and they are smaller than in C. dirus and T. platensis Mercerat, 1891. The metacromion is laminar and more slender in Ch. brachyurus. The astragali are similar to T. platensis, but the heads are more medially projected in the former. The astragalus of Ch. brachyurus is more elongated and narrow, with a slender

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head. The astragalar foramen has been recorded as a variable feature in Ch. brachyurus, Dusicyon gymnocercus (Fischer, 1814) and T. platensis (Ameghino, 1906; Prevosti, personal observations). The metacarpals and cuboid are proportionally longer and more slender in Ch. brachyurus. Genus CANIS Linnaeus, 1758 CANIS DIRUS Leidy, 1858 Figure 5; Table 1 Canis primaevus LEIDY, 1856, p. 167; (non HODGSON, 1833). Canis dirus LEIDY, 1858, p. 21. Canis indianensis LEIDY, 1869, p. 368. Canis mississippiensis ALLEN, 1876, p. 49. Canis ayersi SELLARDS, 1916, p. 152. Aenocyon dirus (LEIDY, 1858); MERRIAM, 1918, p. 533. Description.⎯The I3 is very large, possessing a strong principal cusp with a fully developed mesiolingual crist and lingual cingulum, a distally curved principal cusp, and no accessory cups. The p4 is large and possesses a low, robust, and mesiodistally expanded principal cusp. It also bears a well developed distal accessory cusp, distal and lingual cingula, and a very sharp mesiolingual cristid. A secondary distal accessory cusp is insinuated but not fully separated from the distal cingulum. The robust horizontal ramus of the MBLUZ-P-1940 bears two mental foramina on the lateral surface, a large one below the p1 and another small one below the p3. The p2 alveolus is partially reabsorbed and the canine root is large (L: 17.15). Material examined.⎯MBLUZ-P-2388: right p4; MBLUZ-P-1941: left I3; MBLUZ-P-1940: fragment of right mandible with the alveolus and roots of the c1 and p1–3. Occurrence.⎯Locality 185 of Inciarte (Zulia, Venezuela).

Discussion.⎯The morphology of the I3 and p4 are similar in C. dirus and C. nehringi (Ameghino, 1902) (Berta, 1988; Fig. 5). The development of the mesiolingual crist and the lingual cingulum is only present in South America in these two species. In Protocyon and Theriodictis the principal cusp is more acute. Morphological features of the p4 (e.g., shape of the principal cusp; development of the lingual cingulum) are absent in South American large canids other than C. dirus and C. nehringi. The size of these teeth are within the range of variation of C. dirus (see Merriam, 1912; Nowak, 1979; Berta, 1988), but the p4 is larger than in C. nehringi. Canis nehringi is known only from the holotype from the Pampean Region of Argentina. It is very similar and phylogenetically close to C. dirus (Berta, 1988), and thus very likely a junior synonym of the latter species. MBLUZ-P-1940 is not diagnostic, but its size is larger than that of all other South American canids with the exception of C. dirus. Genus UROCYON Baird, 1758 UROCYON cf. U. CINEREOARGENTEUS (Schreber, 1775) Figure 6; Table 4 Canis cinereo argenteus SCHREBER, 1775, pl. 92. Canis virginianus SCHREBER, 1775, p. 585. Urocyon seminolensis SIMPSON, 1929, p. 575, fig. 2a, 2b; ARATA, 1959, p. 133. Urocyon atwaterensis GETZ, 1960, p. 363–364, fig. 1a, 1f. Urocyon minicephalus MARTIN, 1974, p. 70, fig. 3.10. Description.⎯the occipital presents a convex, wide, and low inion, while the lambdoid crests are strong and widen progressively towards the inion. The paraoccipital process is completely fused to the tympanic bulla, and lacks a free tip. The parietal shows a wrinkled dorsal surface, while the fragmentary right parietal (MBLUZ V 2824) has a wide lyriform area laterally limited by a strong temporal ridge. This temporal ridge extends to near the suture with the occipital. The lyriform area is concave along the medial side of the temporal ridge and flat or slightly convex for the rest of its extension. Below the temporal ridge, the parietal presents a wrinkled surface. In MBLUZ-P-2235 the mastoid process is a weak crest and forms a nearly flat surface. The tympanic bulla is small, but it possesses a well developed external acoustic meatus and an incomplete anteroventral intrabular septum. The subarcuata fossa and the internal acoustic meatus can be observed on the dorsal surface of the petrosum. Dorsal to the temporal crest, the surface of the temporal is wrinkled. Material examined.⎯MBLUZ-P-2235: fragment of left temporal with the tympanic bulla, the petrosal and the mastoid; MBLUZ-P-2824: fragment of right parietal; MBLUZ-P-2923: incomplete occipital.

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FIGURE 5—Specimens of Canis dirus Leidy, 1858 from Inciarte (Zulia, Venezuela). Right p4 (MBLUZ-P-2388) in labial (1) and lingual (2) views. Left I3 (MBLUZ-P-1941) in mesiolabial (3) and occlusal (4) views.

Occurrence.⎯Locality 198 of Inciarte (Zulia, Venezuela), middle level.

Discussion.⎯The presence of strong temporal crests and a wide lyriform area, a wrinkled dorsal surface of the parietals and temporals, the wide lamdoidal crest, and the shape of the inion are typical features of Urocyon (Mivart, 1890; Hall and Kelson, 1959; Clutton-Brock et al., 1976; Kurteń and Anderson, 1980; Fritzell and Haroldson, 1982; Moore and Collins, 1995; Munthe, 1998; Prevosti, personal observations; Fig. 6). Cerdocyon Hamilton-Smith, 1839 and Dusicyon spp. are similar in size but the inion is narrower, while the temporal crests and the lyriform area are different in shape. In these other genera the dorsal surface of the parietal and temporal is smoother. The mastoid process possesses the plesiomorphic condition that is restricted to the ‘Vulpini’ (sensu Tedford et al., 1995). In Otocyon megalotis (Desmaret, 1822) the occiput is proportionally lower. The overall sizes of these specimens are within the variation range of recent U. cinereoargenteus (Table 4). At the moment there are three valid species of Urocyon, the extinct U. progressus, the recent U. cinereoargenteus (Grey Fox), and U. littoralis (Baird, 1758) (Island Fox) (see Hall and Kelson, 1959; Stevens, 1965; Kurteń and Anderson, 1980; Wozencraft, 1993). The extinct species is slightly larger than U. cinereoargenteus, and has a somewhat narrower braincase, narrower lyriform area, and stronger temporal ridges (Stevens, 1965; Kurteń and Anderson, 1980). In contrast, the linear measurements of the Island Fox are 20%–30% smaller than those of the grey fox, the temporal ridges are weaker, and the lyriform area is wider and more convex (Wayne et al., 1991; Moore and Collins, 1995). ‘‘U. minicephalus’’ (assigned to U. cinereoargenteus by Kurteń and

Anderson, 1980) has a much narrower lyriform area and occiput (Martin, 1974). Unfortunately, the Inciarte specimens are fragmentary, which makes comparison difficult, but in size and morphology (i.e., temporal ridge and lyriform area) they are indistinguishable from U. cinereoargenteus and allow us to assign the Inciarte specimens to U. cf. U. cinereoargenteus. CANIDAE Table 3 Description.⎯MBLUZ-P-2387 comprises the glenoid cavity of the temporal, and the postglenoid foramen. The atlas possesses caudally expanded wings with straighter lateral borders, well developed ventral and dorsal tubercles, and a wide transverse foramen and alar notch. The last tubercle is bifid. The axis shows the typical canid morphology. Cervical vertebra MBLUZ-P-3701 has a large and wide neural arch, which possesses two caudal processes on its dorsal surface. The pleurapophyses are bifid and caudally expanded. MBLUZ-P-2065 is very deteriorated but includes a short body, with slanting articular facets and short transverse processes. The anapophyses are moderately developed in the lumbar vertebra, MBLUZ-P-1859, and the neural processes are low and long with a square shape in lateral view. The anterior articular facet of this vertebra is low and kidney-shaped. MBLUZ-P2470 presents a short body with reniform articular facets. The caudal vertebra, MBLUZ-P-2203, has a long body and small prezygapophyses, while caudal vertebra MBLUZ-P-3922 is shorter and does not develop prezygapophyses. The other caudal vertebrae have post-prezygapophyses, neural arches, and transverse processes. In MBLUZ-P-2596 the tibial tuberosity is well developed and expanded, the condyles also are expanded caudally. The muscular groove is deep and limited by strong cranial and lateral tubercles. The caudal face of the diaphysis has a narrow and medially displaced area of origin for the caudal tibial and flexor digitalis longus muscles. The scapholunar has a large palmar process, a sigmoidal radial articular facet, and a well developed


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FIGURE 6—Specimens of Urocyon cf. U. cinereoargenteus (Schreber, 1775) from Inciarte (Zulia, Venezuela). Incomplete parietal (MBLUZ-P-2824) in dorsal view (1). Caudal view (2) of occipital region (MBLUZ-P-2923). Incomplete right temporal plus mastoid (MBLUZ-P-2235) in lateral (3) and ventrocaudal (4) views.

proximal process. The first metacarpals are well developed and possess generalized morphology (see Evans, 1993). The phalanges and distal sesamoids also have generalized morphology represented in the majority of the recent canid species. The sacrum (MBLUZ-P-3583) comprises three sacral vertebrae, and has caudolaterally-oriented large transverse processes on the third vertebra. The distal humerus portion (MBLUZ-P-4714) has a large supratrochlear foramen and a well-expanded medial epicondyle. It also possesses a well delimited and spherical capitulum on the distal articular facet. The calcaneum (MBLUZP-2921) presents a subcircular sustentacular facet, and a wide groove which separates it from the ectal facet. The trochlear process appears well-developed and distally displaced, while the dorsal table bears a strong longitudinal crest. Material examined.⎯MBLUZ-P-2387: fragment of left temporal; MBLUZ-P-3922: eighth? caudal vertebra without epiphyses; MBLUZ-P3700: incomplete atlas; MBLUZ-P-3386: incomplete atlas; MBLUZ-P-6581: axis; MBLUZ-P-3701: third? cervical vertebra; MBLUZ-P-2065: seventh cervical vertebra; MBLUZ-P-3709: incomplete lumbar vertebra; MBLUZ-P2421: body of the first? lumbar vertebra; MBLUZ-P-1859: second? lumbar vertebra; MBLUZ-P-2470: body of the seventh? lumbar vertebra; MBLUZP-4390: sixth or seventh caudal vertebra; MBLUZ-P-2143: fourth or fifth caudal vertebra; MBLUZ-P-2203: tenth? caudal vertebra; MBLUZ-P-2969: third caudal vertebra; MBLUZ-P-4348: fourth caudal vertebra; MBLUZ-P4051: proximal fragment of rib; MBLUZ-P-3012: proximal fragment of rib; MBLUZ-P-2596: proximal fragment of left tibia; MBLUZ-P-2108: right scapholunar; MBLUZ-P-3071: first left metacarpal; MBLUZ-P-2072: first left metacarpal; MBLUZ-P-2190: distal fragment of metapodial; MBLUZ-P-1990: distal fragment of metapodial; MBLUZ-P-2547: distal fragment of metapodial; MBLUZ-P-2887: proximal phalanx of the third or fourth digit; MBLUZP-4502: proximal phalanx of the third or fourth digit; MBLUZ-P-2458:

TABLE 4—Cranial measurements (mm) of U. cf. U. cinereoargenteus (Schreber, 1775) from Inciarte (Zulia, Venezuela).

MBLUZ-P-2235 MBLUZ-P-2923

LB

WB

17.35

11.75

WCON

WFM

HFM

22.9

14.15

9.9

proximal phalanx of the third or fourth digit; MBLUZ-P-3691: proximal phalanx of the third or fourth digit; MBLUZ-P-2173: proximal phalanx of third or fourth digit; MBLUZ-P-2455: proximal phalanx of the second or fifth digit; MBLUZ-P-4424: proximal phalanx without proximal epiphysis; MBLUZ-P4391: proximal phalanx without proximal epiphysis; MBLUZ-P-2869: proximal phalanx of the second or fifth digit; MBLUZ-P-1939: proximal phalanx of the second or fifth digit; MBLUZ-P-2278: proximal phalanx of the second or fifth digit; MBLUZ-P-3985: proximal phalanx of the second or fifth digit; MBLUZ-P-4104: proximal phalanx of the second or fifth digit; MBLUZ-P4494: middle phalanx of the second or fifth digit; MBLUZ-P-2539: middle phalanx of the second or fifth digit; MBLUZ-P-2577: middle phalanx of the second or fifth digit; MBLUZ-P-2950: middle phalanx of the third or fourth digit; MBLUZ-P-2279: middle phalanx of the second or fifth digit; MBLUZP-2992: middle phalanx of the third or fourth digit; MBLUZ-P-4034: middle phalanx of the third or fourth digit; MBLUZ-P-2902: middle phalanx of the second or fifth digit; MBLUZ-P-2951: middle phalanx of the third or fourth digit; MBLUZ-P-2106: middle phalanx of the third or fourth digit; MBLUZP-2602: distal phalanx; MBLUZ-P-4243: distal phalanx; MBLUZ-P-2144: distal phalanx; MBLUZ-P-2100: distal phalanx; MBLUZ-P-4455: distal phalanx; MBLUZ-P-2967: distal phalanx; MBLUZ-P-2929: distal phalanx; MBLUZ-P-3689: distal phalanx; MBLUZ-P-2438: distal sesamoid; MBLUZP-4857: distal sesamoid; MBLUZ-P-3747: distal sesamoid; MBLUZ-P-3746: distal sesamoid; MBLUZ-P-2014: distal sesamoid; MBLUZ-P-3583: sacrum; MBLUZ-P-4714: distal fragment of left humerus; MBLUZ-P-2921: right calcaneum. Occurrence.⎯MBLUZ-P-2387, MBLUZ-P-1859, MBLUZ-P-1939, and MBLUZ-P-6581 come from locality 185 of Inciarte (Zulia, Venezuela), and the others specimens are from the middle level of the locality 198.

Discussion.⎯Except three remains (see below) the size of these specimens agrees with a large canid species (Table 3), but we couldn’t assign them to a specific genus because they don’t show diagnostic characters. A few specimens do present characters enabling differentiation from some species. For example, the ungual processes of the distal phalanges are more robust and blunt than in Ch. brachyurus. The first metacarpal is proportionally shorter than in this species. The axis is shorter relative to width than in

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Ch. brachyurus. It is highly possible that the specimens collected at locality 198 pertain to P. troglodytes, because their size and morphology agree with this species, but we cannot confirm this supposition with certainty. MBLUZ-P-1859 could be assigned to C. dirus, because its size is comparable to the latter species, which is the only canid present at the locality 185. MBLUZ-P-3583, MBLUZ-P-4714, and MBLUZ-P-2921 correspond in size to small canid species (e.g., Dusicyon, U. cinereoargenteus, Cerdocyon; see Table 3). Although we cannot assign these specimens definitively to any specific genus or species, their general appearance suggests that they probably belong to U. cinereoargenteus. IMPLICATIONS OF THE NEW FOSSIL CANID RECORDS

The canids of Inciarte are represented by a large number of specimens (艐120), most of which are fragments of isolated anatomical elements that appear to represent only a few individuals. The minimal number of individuals is as follows: one U. cf. U. cinereoargenteus, one C. dirus, two P. troglodytes (based in two fragments of right mandibles with m1) and three Protocyon sp. (based on three left M1). Additionally, if we consider that all bones of large canids found at the locality 198 are from the same taxon, there are only a total of three individuals. Protocyon is a genus restricted to South America (see Berta, 1988; Prevosti et al., 2005). The northern previous records of Protocyon troglodytes are from southern Ecuador (Santa Elena) (Hoffstetter, 1952; Berta, 1988) and northeastern Brazil (Bahia, Ceara´, Piaui; Cartelle, 1999; Prevosti et al., 2005), both of these areas are 1500 km or more from Inciarte. The presence of this South American taxon near the Panamanian Bridge, the ‘‘door’’ of South America, raises the possibility of its immigration into Central America. Protocyon is found in open environments (grasslands), mosaics of forest and cerrado (dry deciduous tropical forest) (Berta, 1988; Cartelle and Langguth, 1999). The tree savanna environment reconstruction for the middle level of Inciarte (Rincoń, 2005) agrees with these observations of preferred habitat. The more closed environment of the upper level suggests that this species could inhabit different vegetation types, which is in agreement with its wide geographical range (Prevosti et al., 2005). The chronological and geographical position of Inciarte raises the possibility that P. troglodytes could have crossed the Panamanian Bridge to Central America during the late Pleistocene, if as suggested by Webb (1991, 1999, 2003; Webb and Rancy, 1996) during glacial periods some kind of grassland or open forests corridor were established throughout the Panamanian Land Bridge. Paleoenvironmental studies from southern Panama (e.g., Colinvaux, 1996, 2003; but see Schubert, 1989) do not agree with the grassland hypothesis because the authors found lowland rain forest and mountain forest descending to 800 m during the last glacial cycle (艐120–10 Ka BP). On the other hand, during the glacial stages, grassland corridors could exist along or near seacoasts in areas now under the sea (e.g., Campbell, 1982). Clearly, more paleontological studies should be performed in Central America and northern South America to explore the possibility that Protocyon invaded Central America sometime during the Pleistocene. Contrasted with its widespread range as documented by numerous localities in North America, C. dirus is only known from three localities in South America other than Inciarte: Talara (Piura, Peru´); Quebrada del Puente Alto (Tarija, Bolivia), and Muaco (Falcoń, Venezuela) (Nowak, 1979; Dundas, 1999). Talara has been dated between 13–14 Ka BP (Dundas, 1999) and Muaco between 16.375 ⫾ 0.40 and 9.030 ⫾ 0.24 years BP (Bocquentin, 1979), while Quebrada del Puente Alto is assigned to the Lujanian but lacks isotopic dates or precise stratigraphic provenance (Berta, 1988; Dundas, 1999). The stratigraphic position of Locality 185 suggests that it is younger than Locality 198, and less than 25–

27 Ka BP, but we cannot constrain the younger age of these specimens. The paleontological record of this species indicates it is older in North America, where it has been found in Sangamonian sites (130 Ka BP; Dundas, 1999), suggesting a late Pleistocene immigration event into South America. The fossil record clearly contradicts the hypothesis of Nowak (1979; see also Nowak, 2002) of a South American origin for C. dirus. Berta (1988) interpreted the immigration of this taxon in light of the Webb model and suggested that C. dirus crossed throughout the Andean Corridor (a high road of cool, dry, unforested habitats) along the Cordillera de los Andes. The two records of C. dirus in Venezuela are outside this corridor and fall in the savannah dispersal route east of the Andes (Berta, 1988; Webb, 1991). This is in agreement with the wide geographical and altitudinal range of this species, as well as with its varied habitats (Dundas, 1999). Clearly this species expanded its range through many habitats and was not restricted to either of these two corridors. The previous record of C. dirus in Venezuela, at Muaco (vide supra), was mentioned by Royo y Go´mez (1960), but only fully described by Bocquentin (1979). Berta (1988) could not study these specimens because they were lost. Recently one of us (AR) found the skull described by Bocquentin (1979) at the Universidad Central de Venezuela, with the number ‘‘VF-?’’ The morphology of the skull is consistent with the description by Bocquentin (1979), and clearly belongs to C. dirus. An interesting question is the ‘sympatry’ of C. dirus and Protocyon. Lemon and Churcher (1961) noted that C. dirus is absent from the La Carolina fauna where Protocyon has lived and inversely, Protocyon is absent from Talara. This is striking because the sites share similar faunas and are in close proximity to each other. Unfortunately, La Carolina lacks isotopic dates. Lemon and Churcher (1961) discarded competition as the cause for their mutual exclusion and the absence of Protocyon from Talara (C. dirus is bigger and could actively displace Protocyon), instead suggesting that the two localities are diachronic, with an older age for the La Carolina site predating arrival of C. dirus into South America. The two species are recorded together at Inciarte but the stratigraphic information suggests that Locality 185 is younger than 198, which supports Lemon and Churcher’s hypothesis. Direct dates of these fossils may be useful to constrain their ages and test this hypothesis. Urocyon is represented in North America during the Blancan (4.5–1.8 Ma BP) by U. progressus Stevens, 1965, but undescribed specimens extend the chronologic range of the genus to the Hemphilian (9–5 Ma BP) (Wang et al., 2004), even tentatively to the late Clarendonian (Munthe, 1998). Urocyon cinereoargenteus has been recorded from numerous localities of Irvingtonian, Rancholabrean, and Holocene age in North America, and the species could extend back to the late Blancan (Kurteń and Anderson, 1980; Fritzell and Haroldson, 1982; Graham and Lundelius, 1994). By contrast, fossils of the third species (U. littoralis) endemic to the Channel Islands on the Pacific coast (California, United States of America) are also known from Pleistocene and Holocene sites within the recent distribution of the Island Fox. Extant U. cinereoargenteus has a wide geographic range that extends from southern Canada to northwest South America (Colombia and Venezuela), with the exception of the Great Plains and portions of the mountainous portions of the northwestern United States of America and eastern Central America (Hall and Kelson, 1959; Fritzell and Haroldson, 1982; Fuller and Cypher, 2004). Some authors argue that its absence from the fossil record and its limited Recent range in South America, in contrast to the wide Recent and fossil distribution in North America, suggest that it is a recent immigrant to South America (Langguth, 1970; Eisenberg, 1989; Linares, 1998). Conversely, Hershkovitz (1972) hypothesized that the Grey Fox spread to South America earlier

PREVOSTI AND RINCON—PLEISTOCENE CANIDS FROM THE LATE PLEISTOCENE OF VENEZUELA (his ‘‘Faunal Stratum Va’’) with other, now extinct North American mammals (e.g., mastodons). While the North American Miocene and Pliocene records of the genus and the phylogenetic position of the Grey Fox agree with a Neartic origin of this lineage (Wang et al., 2004), they do not provide data on the timing of immigration of U. cinereoargenteus into South America. The specimens of Inciarte are in agreement with the hypothesis of Hershkovitz (1972), and indicate that the time of the immigration is around 25–27 Ka BP or earlier. The Grey Fox utilizes a variety of habitats. It occurs in several types of forested landscapes, such as deciduous pine forest interspersed with old fields and scrubby woodlands, mountain forest, thick brush habitats, and riparian forest. It also occurs in mixed habitats with agricultural fields and woodlands, as well as semiarid areas of the the southwestern United States of America and northern Mexico (Fuller and Cypher, 2004). In South America it is restricted primarily to the montane forest of the Cordillera Oriental in Colombia and the Andes and Cordillera Central of Venezuela (Bisbal, 1982; Mondolfi and Bisbal, 1985; Eisenberg, 1989; Linares, 1998) between elevations of 100–700 m (Mondolfi y Bisbal, 1985). There are records in the northern parts of the ‘Llanos’ grassland biome, but there it is associated with tree savannas and open forests (Mondolfi and Bisbal, 1985). Intriguingly, there are no recent records of the species from the Sierra de Perija´ or the Maracaibo area; however, we cannot exclude the possibility that its absence is an artifact of the scarce number of studies in the region or a consequence of the anthropic alteration in historic times. The record of this species at Inciarte suggests the presence of some kind of forest vegetation. CONCLUSIONS

Urocyon cf. U. cinereoargenteus, P. troglodytes, Protocyon sp., and C. dirus are recorded for the late Pleistocene locality of Inciarte (Venezuela). This constitutes the first fossil record of Urocyon in South America and suggests that the youngest date for the immigration of U. cinereoargenteus is 25–27 Ka BP. The specimens of P. troglodytes and Protocyon sp. are the first occurrences of these taxa in Venezuela, and extend the distribution of the genus 1,500 km north of its previous records, placing it near the Panamanian isthmus. Inciarte is a new locality for C. dirus and increases the number of localities in South America to four. The age of U. cf. U. cinereoargenteus, P. troglodytes, and Protocyon sp. is near 25–27 Ka BP, but, based on the stratigraphic evidence, C. dirus is younger. ACKNOWLEDGMENTS

We thank J. Moody, G. McDonald, T. Barros, R. Rivera, E. Infante, L. Liseth, N. Cifuentes, H. Prieto, and A. Viloria for all of their help during this work. K. Aaris is thanked for the casts of P. troglodytes of the Lund Collection. R. Tedford provided useful comments. The comments of two anonymous reviewers, and of the Production Editor and E. Scott, improved the quality of this manuscript. This is a contribution to the projects UNLP N-336, UNLP N-441, and PICT 8395. REFERENCES

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ACCEPTED 18 JUNE 2006